Normal-danger-signal system.



L. A. HAWKINS.

' NORMAL DANGER SIGNAL SYSTEM.

APPLICATION TILED JULY 23, 1908. RENEWED NOV. 12, 1910. 1,Q91,1 34= Patented M81224, 1914 2 ST EETS-SHEBT 1.

ILVYTNEESEE/ ZNYENTUH W M M AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA c4 L. A. HAWKINS. NORMAL DANGER SIGNAL SYSTEM. APPLIOATION FILED JULY 2a, 1908. RENEWED H0112; 1910.

1,O91,1 34. Patented Mar. 24, 1914,

2 I BEETS-SHEET 2.

FIG. 2

WITNESSES lNVE NTOR COLUMBIA PLANOGRAPH 00.. WASHINGTON. u. (2.

UNITED STATES 1 PATEN OFFICE.

LAURENCE A. HAWKINS, OF SCHENECTADY, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE UNION SWITCH AND SIGNAL COMPANY, A CORPORATION OF PENNSYLVANIA.

Specification of Letters Patent.

Patented Mar. 24, 1914.

Application filed July 23, 1908, Serial No. 444,898. Renewed November 12, 1910. Serial No. 592,133.

To all whom it may concern:

Be it known that I, LAURENCE A. HAW- KINS, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Normal- Danger-Signal Systems, of which the following is a specification.

toms for electric roads having both rails conductively continuous for all currents, and

its object is to provide for such roads an eflicient signal system operating on the normal danger principle.

My invention consists in providing sources of alternating current connectedvacross the rails at intervals, the sources being all of the same frequency and phase and forming the only cross-connections between the rails when the rails are unoccupied by a car or train, so that ordinarily nocurrent, except leakage current, flows, and arranging the track-relays each with a winding connected in shunt to a short length of rail, so that the relay is normally deenergized, and all the signals stand at danger when no trains are running. When a train is at any point on the track, it shortcircuits the rails at that point and produces a flow of current toward it from adjacent sources. This flow of current from the sources ahead of the train energizes a track-relay ahead of the train to clear a signal. The relays back of the train are not affected, since the flow of current is in the wrong direction for energizing them.

Since it is ordinarily desirable to employ home and distant signals, or their equivalent, to indicate the condition of two blocks ahead of the train, I further provide means controlled by the energization of the trackrelay for establishing a cross-connection be tween the rails in such a manner as to energize a second track-relay. This cross-connection may conveniently be established by the clearing of the signal controlled by the first track-relay. In order to prevent the second signal, when it is'cleared, from similarly clearing the third signal ahead, I provide means for preventing the establishing of the cross-connection by the clearing of a signal when the signal in the rear is cleared.

My invention will best be understood by reference to the accompanying drawing, whlch shows diagrammatically a block signal system arranged in accordance with my invention.

Referring first to Figure 1 A represents the track-rails of an electric railway, which rails may be conductively continuous for all y currents throughout the length of the road. My invention relates to block signal sys-' B represents an alternating-current generator for supplying current for the signal circults; Z2 represents line-wires supplied from this generator. C, C and C represent supply transformers connected across the rails at intervals. All these are similarly connected both to the line-wires and to the rails, so that since the transformer secondaries form the only cross-connections between the rails as long as no trains are running, no current but leakage current normally flows. I 0 0 represent impedances in series with the secondaries of the transformers. These .impedances serve to prevent saturation of the transformers by powercurrent, to limit the short-oirouit current when a train stands directly over the' terminals of the transformer, and to reduce the voltage impressed across the rails when the rails are cross-connected for a purpose hereinafter explained. D and D repre sent track-relays, which are shown diagrammatically as of the two-phase induct-ion type. Each track relay. comprises a short-circuited secondary (Z, actuating the relay contacts; Two windings (Z1 are connected in shunt to short opposite rail lengths adjacent to one of the transformers and a cooperating winding d supplied with current independently of the track-circuits. Any suitable phasecontrolling means, such as the'condenser (i may be employed to give the proper phaserelation between the currents in the relay windings al and (Z E E and E? repre sent home signals, and F F and F represent distant signals. guards the portion of the track between two adjacent transformers,that is, the home signal E guards the portion of the track between transformers C and C and signal E the portion of the track between transformers G and C the direction of traffic being as indicated'by the arrow. Each home signal is provided with two contacts 6 and 6 which are normally open, and are closed Each home signal when the signal is cleared. G G and G represent normally energized relays having their contacts in circuit with contacts 6 of the home signals, and their windings in circuit with the back contacts of the track relay for the block in the rear.

As has been said heretofore, no current flows in the rails, except leakage current, when no trains are running, and since the track winding of each relay is adjacent to a transformer, the leakage current that passes through its track windings is that from that tracktransformer, and is in. the wrong direction to energize the relay, even if the quantity of the leakage current were suiiicient to do so. If, however, a train should enter the block to the right of transformer G, itwould draw current from transformer C, and because of the voltage-drop across the rails due to this current flow in the transformer windings and in the impedance 0,; the voltage across the rails at transformer C will be considerably lower than that across the rails at transformer C Consequently, current will flow from transformer C also toward. the right, and this current flowing through the rails between transformer C and C will energize thewindings d of relay D and consequently will cause that relay to pick up its contacts, clearing signal E The clearing of this signal closes a circuit across the railsthrough contacts 6 and the contacts of the normally energized relay G. This short-circuiting of the rails at transformer O. increases the flow of current from transformer C and in turn lowers-the potential which this transformer impresses on the track, so as to produce a flow of current from transformer C toward the right, so as to energize relay D Relay D closes the circuit of the operating mechanism of home signal E and this signal clears. When signal? E has cleared, its contacts 6 close a circuitthrough contacts 6 of signal E and through. the operating mechanism of distant signal; F so as to clear that signal. Although the contact 6 of home signal E is closed, this home signal does not establish a connection across the rails, since relay G is denergized, track relay D being energized, and its back contacts opened. Thus, the clearing of home signal E is prevented until. the train, entering the block guarded by home signal E puts that signal at danger.

If, when a signal clears, it cross-connects the rails'at the'signal, it thereby short-circuits; the transformer at the signal through the impedance in series with the transformer secondary, unless the transformer circuit is opened; On account of the impedance in cluded in this short-circuit, the short-circuiting does-no harm, and it is not necessary to open? the transformer circuits. If desired, however, theatransformer circuits may be opened so as to economize current. In Fig.

2 I have shown one means for doing this. This means comprises back contacts on each signal and on each relay G and G etc. The back contacts of each signal and of each adjacent relay G G etc. are in multiple and the two are included in series with one winding of the adjacent transformer, which winding as here shown is the primary. Since each signal is normally at danger, its contacts normally close the transformer circuit, but when the signal clears, it opens the transformer circuit before it establishes the cross-connection between the rails, provided the adjacent relay G G etc. is energized, as in the case if a train is in the first block in the rear of the block guarded by the signal. If, however, a train is two blocks away, the clearing of the signal, in response to the clearing of the home signal in the rear. would not open the circuit of transformer C, since the adjacent relay G G or G would be deenergized, because the signal in the rear being clear, the track relay in the rear is energized, so that the circuit of such relay G, G or G is open. The back contacts of relay G G or G therefore, shunt the back contacts on the adjacent signal, so that the relay G, G or G acts to prevent the signal E both from opening the circuit of transformer C and from establishing a cross-connection across the rails at signal E, either of which operations would throw the signal at the rear to danger.

The operation of the apparatus shown in Fig. 2 will now be apparent in view of the explanation of the operation of that shown in Fig. l.

I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the appended claims to cover all modifications which are within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,-

1. In a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating current of the same frequency and phase connected across the rails at intervals, normally deenergized track-relays each having a winding connected in shunt to a portion of rail of sufiicient length to provide the drop necessary to energize the said winding, and signals normally at danger controlled by said relays.

2. In a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating current of the same frequency and phase connected across the rails at intervals, said sources normally forming the only cross-connections between said rails, track-relays each having a winding connected in shunt to a portion of rail of suflicient length to provide the drop necessary to energize the said winding, and

signals normally at danger controlled by said relays.

3. I11 a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating current of the same frequency and phase connected across the rails at intervals, normally deenergiz'ed relays each having a winding in shunt to a portion of rail adjacent. to a source, said portion of rail being of suflicient length to provide the drop necessary to energize the said winding, and signals controlled by said relays, each guarding a length of track between adjacent sources.

4. In a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between said rails, track-relays each having a winding connected in shunt to a portion of rail of sufficient length to provide the drop necessary to energize the said winding, signals normally at danger controlled by said relays, and means actuated by the movement of a signal to clear for cross-connecting the rails.

5. In a block slgnal system, 1n combina- .tionwith an electric railway having both rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a winding connected in shunt to a portion of rail of sufficient length to provide the drop necessary to ener- "gize the said winding, signals normally at danger controlled by said relays, means actuated by the movement of a signal to clear for cross-connecting the rails, and means for preventing the establishing of the cross-connection when the signal in the rear is at clear.

6. In a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a winding connected in shunt to a portion of rail of suflicient length to provide the drop necessary to energize the said winding, signals normally at danger controlled by said relays, means actuated by the movement of a signalto clear for cross-connecting the rails, and means for preventing the establishing of the cross-connection when the block in the rear of the signal is unoccupied.

7. In a block signal system, in combination with an electric railway having both 1 rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a win-ding connected in shunt to a portion of rail of sufficient length to providethe drop necessary to energize the said winding, signals normally at danger controlled by said relays, means actuated by the movement of a signal to clear for crossconnecting the rails, and a normally energized relay having its contacts included in the cross-connection arranged to be deenergized when the signal in the rear is at clear.

8. In a block signal system, in combination with an electric railway having both ralls conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only cross connections between said rails, track relays each having a winding connected in shunt to a portion of rail of sufficient length to provide the dropnecessary to energize, the said winding, and each having back contacts, and signals normally at danger controlled by said relays, means actuated by the movement of a signal to clear'for cross-connecting the rails, and a relay having its contacts in cluded in the cross-connection and its winding in circuit with back contacts of the track relay for the block in the rear.

9. In a block signal system, in combination with an electric railway having both rails conductively continuous for all cur rents, sources of alternating voltage'of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a winding connected in shunt to a portion of rail of sufficient length to provide the drop necessary to energize the saidwinding, signals normally at danger controlled by said relays, and means controlled by a track relay when energized for cross-connecting the rails to energize a second track relay.

10. In a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the 'rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a winding connected in shunt to a portion of rail of 'sufiicient length to provide the drop necessary tojenergize the said winding, signals normally at danger controlled by said relays, and means con trolled by a track relay when energized for crossconnecting the rails adjacent to a source to energize a second track relay and for opening the circuit of said source.

11. In a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a winding connected in shunt to a portion of rail of sufficient length to provide the drop necessary to energize the said winding, signals normally at danger controlled by said relays, means controlled by a track relay when energized for crossconnecting the rails adjacent to a source to energize a second track relay and for opening the circuit of said source, and means for preventing the establishing of the cross-connection and the opening of the circuit of the source when the block in the rear is unoccupied.

12. In a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a winding connected in shunt to a portion of rail of suificient length to provide the drop necessary to energize the said winding, signals normally at danger controlled by said relays, means actuated by the movement of a signal to clear for crossconnecting the rails and for opening the circuit of the adjacent source. 13. In a block signal system, in combination with an electric railway having both rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a winding connected in shunt to a portion of rail of suflicient length to provide the drop necessary to energize the said winding, signals normally at danger controlled by said relays, means actuated by the movement of a signal to clear for crossconnecting the rails and for opening the circuit of the adjacent source, and means for preventing'the establishing of the cross-connection and the opening of the circuit of the source when the block in the rear of the signal is unoccupied.

145'. "In a block signal system, the combination with an electric railway having both rails conductively continuous for all currents, sources of alternating voltage of poor regulation of the-same frequency and phase connected acrossthe rails at intervals, said sources normally forming the only crossconnections between said rails, track relays each having a winding connected in shunt to a portion of rail of sufficient length to provide the drop necessary to energize the said winding, signals normally at danger controlled by said relays, and means controlled by a track relay when energized for establishing connections for energizing a second track relay.

15. In combination with a railway having both track rails conductively continuous for all currents, sources of alternating signaling voltage of poor regulation connected across the rails at intervals, a track relay for each section of the railway included between the connections of adjacent sources, each relay having a winding connected in shunt to a portion of rail in said section, the said portion of rail being of sufiicient length to energize the relay winding by the flow of signaling current from the source next in advance of the relay when the rails in the section next in the rear of the relay are cross-connected, and a signal for each section controlled by the track relay for that section.

16. In combination with a railway having both track rails conductively continuous for all currents, sources of alternating signaling voltage of poor regulation connected across the rails at intervals, a track relay for each section of the railway included between the connections of adjacent sources, each relay having a winding connected in shunt to a portion of rail in said section, the said portion of rail being of sufiicient length to energize the relay winding by the flow of signaling current from the source next in advance of the relay when the rails in the section next in the rear of the relay or in the exit end of the second section in the rear of the relay are cross-connected, a signal for each section, each controlled by the track relay for the section, and means controlled by each signal and by the track relay for the section next in the rear for cross-connecting the rails adjacent the exit end of the last mentioned section when the signal is in clear position and the said relay deenergized.

17. In combination, an electric railway having both track rails conductively continuous for all currents, sources of alternat ing current of the same frequency and phase connected across the rails at intervals, said sources normally forming the only crossconnections between the rails, an impedance included in the connection of eachsource with the rails for causing a considerable drop of voltage across the rails when the rails are cross-connected by other means,

track relays each having a Winding con- In Witness whereof, I have hereunto set nectedi in sllllunt to a BOItIlIOIIdOf rail of 1suflimy hand this 21st day of July, 1908.

cient engt to provi e t e rop in v0 tage necessary to energize the relay, signals nor- LAURENCE HAWKINS mally at danger controlled by said relays, Witnesses: and means controlled by the movement of a BENJAMIN B. HULL,

signal to clear for cross-connecting the rails. HELEN ORFORD.

aopiel of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. c." a 

